igc: Remove redundant IFCAP_VLAN_HWTAGGING check

Match igb(4) as in f7926a6d0c10. From Vincenzo, this check is redundant
to setup providing us an IGC_RXD_STAT_VP bit and would make for an
unexpected condition if IFCAP_VLAN_HWTAGGING were not set but the tag
was stripped, which would be passed up the stack breaking isolation.

PR: 260068
Approved by: vmaffione
MFC after: 1 month